//move to same color:even
//move to different color:odd
function whoseTurn(positions) {
    var arr = positions.split(';')
    var s = 'abcdefgh';
    var black = s.indexOf(arr[0][0]) + parseInt(arr[0][1]) - 1 + s.indexOf(arr[1][0]) + parseInt(arr[1][1]) - 1;
    var white = s.indexOf(arr[2][0]) + parseInt(arr[2][1]) - 1 + s.indexOf(arr[3][0]) + parseInt(arr[3][1]) - 1;
    return white % 2 === black % 2;
}

